Underwater hydraulic control valves, such as used in controlling production or drilling equipment in underwater wells, such as shown in U.S. Pat. No. 3,993,100, is old.
The present invention is directed to various improvements, one of which is a hydraulically actuated control valve, and another of which is an improved control system utilizing the improved valve in which the control system may be actuated by various control modes. The present invention is directed to a control system and improved control valve in which the control valve is operated in both an electro-hydraulic control mode and a hydraulic mode for operating underwater equipment. The use of an electrical control system provides a faster actuating control system and the use of solenoid actuated pilot valves allows the use of minimum electrical power. In addition, a hydraulic backup control system is used to insure that the control valves may be operated in the event of a failure in the electro-hydraulic control system.